Area Forecast Discussion
Issued by NWS Jacksonville, FL
Issued by NWS Jacksonville, FL
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306 FXUS62 KJAX 061620 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 1220 PM EDT Sat Jul 6 2024 ...New AVIATION... .UPDATE... Issued at 813 AM EDT Sat Jul 6 2024 For the latest NE FL and SE GA Daily Key Messages please visit: https://www.weather.gov/media/jax/briefings/nws-jax-briefing.pdf Upper high remains over forecast area, thus once again afternoon showers/storms will only have sea breeze boundaries to focus on, with greatest coverage over center of nrn FL peninsula where sea breezes converge. Current temp and POP forecasts look fine. Will also leave Heat Advisory in place as is. Given current forecast temperatures, need dew point values of 77 or higher to get heat index values that reach advisory criteria...best chance for that appears to interior areas of ne FL/se GA. E and S of advisory area, afternoon heat index values of 103-107 more likely with mid 70s dew points. && .NEAR TERM... Issued at 304 AM EDT Sat Jul 6 2024 For the latest NE FL and SE GA Daily Key Messages please visit: https://www.weather.gov/media/jax/briefings/nws-jax-briefing.pdf Higher shower and thunderstorm chances today for inland areas as a surface front across GA edges farther south, with a plume of very high precipitable water content (PWAT) of 2.2-2.5 inches settling across SE GA and the Suwannee River Valley this afternoon and evening. This deep layer moisture combined with diurnal instability will fuel scattered to numerous showers and thunderstorms this the afternoon and evening. Given weak 1000-500 mb steering flow < 5 kts, both west and east coast sea breezes will develop and press inland...very slowly...with the deepest convective growth focused near boundary mergers during the late afternoon and early evening. Weak shear and warm mid level temperatures do not favor severe storms, however, the very high moisture content combined with weak storm motion will bring localized flooding rainfall potential and gust wet downbursts winds near 40 mph. Drier air (PWATs < 2 inches) will hug coastal areas today with most moisture below 700 mb. This will limit deep convective growth (thunderstorm) potential and mainly favor showers along the inland progressing east coast and river breezes. Despite increased convection today, the persistent 500 mb dome of high pressure remains in place across the local area. This will continue to bring above normal temperatures with highs again reaching the mid to upper 90s inland to lower 90s coast. This heat combined with juicy dew pts in the mid to upper 70s will once again create heat index values of 105-112 degrees F. A heat advisory is in effect for inland SE GA and much of inland NE FL, west of a Baker to Alachua county line. As a reminder, local heat advisories are issued when forecast heat index values of 108-112 degrees are expected. Tonight, convection will slowly fade in coverage and intensity, likely lingering across SE GA a bit longer compared to NE FL. Given such a saturated airmass and lingering convergent boundaries, a few rouge showers could develop overnight as muggy temps fall into the mid 70s inland to upper 70s/near 80 toward the Atlantic coast. && .SHORT TERM... (Sunday through Monday night) Issued at 304 AM EDT Sat Jul 6 2024 Sunday, cold frontal boundary will stretch from near the FL panhandle to central GA and NE into the coastal Carolinas and will likely not budge much due to the mid to upper level ridging parked over the eastern Gulf/FL peninsula. With the weak surface pressure gradient, both seabreezes should merge inland. Some wet downbursts will present gusty winds, through not expected to reach severe speeds, in the 40-50 mph range. High moisture levels over the area will exceed the 90th percentile (PWATs 2.10-2.30 inches) which along with weak storm motions will create very efficient rainfall rates in heavy downpours with locally heavy rainfall totals of 1-3 inches/isolated 4 inch amounts creating localized flooding in urban and low lying areas. Highs will be in the mid 90s over NE FL into SE GA south of Waycross with low 90s further north towards the Altamaha river basin and around 90 degrees along the beaches. Peak heat index values will range 105-110 degrees and a heat advisory may be issued over much of the area away from the coast. Sunday night, showers and T`storms will dwindle by midnight with mostly cloudy skies remaining from mid and high level cloudiness persisting from earlier T`storms. Lows will be above normal in the mid 70s inland and the upper 70s to near 80 at the coast. Monday will be similar with a very moist airmass and weak pressure pattern allowing both seabreezes to push inland with showers and T`storms becoming numerous by afternoon most prominently near the highway 301 corridor over NE FL and away from the coast in SE GA. Warm mid level temperatures will help preclude a severe T`storm threat, but locally heavy rainfall will be the main hazard along with strong, sub-severe wind gusts 40-50 mph where cell mergers do occur. Highs will be in the low 90s at the coast and I-95 areas with mostly cloudy skies and mid 90s inland where skies will be partly cloudy before T`storms develop. Peak heat index values will range 102-106. && .LONG TERM... (Tuesday through Friday) Issued at 304 AM EDT Sat Jul 6 2024 The forecast pattern will not change overall into next week as mid to upper level ridging remains entrenched from the central Gulf coast into the coastal SE. Bermuda high pressure ridging will build into South FL and bring more southwesterly weak low level steering over the area through Wednesday, focusing the highest coverage of T`storms to the I-95 corridor as the Gulf seabreeze progresses towards the east coast before merging with the pinned Atlantic seabreeze with locally heavy rainfall, frequent lightning, and strong wind gusts from wet downbursts. By Thursday, Bermuda high pressure surface ridge axis will nudge into central FL and then into the area Friday which will allow the best focus to T`storms away from the coast as the Atlantic seabreeze pushes farther inland before merging with the Gulf seabreeze. Temperatures will begin the period near normal Tuesday with highs in the lower 90s and and then warm to above normal the rest of the week as highs inland reach the mid 90s with isolated upper 90s possible and heat advisories may return midweek. Lows will be a little above normal in the low to mid 70s inland and the upper 70s to near 80 at the immediate coast and St Johns river basin. && .AVIATION... (18Z TAFS) Issued at 1220 PM EDT Sat Jul 6 2024 Latest satellite imagery shows plenty of cumulus clouds around TAF sites based at SCT-BKN030-040. Widely scattered SHRA/TSRA will develop along west coast and east coast sea breezes later this afternoon, likely with greatest coverage over central part of ne FL peninsula, including KGNV area, by late afternoon as sea breezes converge...maintaining TEMPO group for TSRA at KGNV 20z-00z, VCTS at other inland TAF sites. Light S to SW winds this afternoon interior areas, with SE winds 6-10kts after passage of east coast sea breeze for eastern TAF sites. Light winds are expected Tonight and Sunday morning with VFR conditions. && .MARINE... Issued at 304 AM EDT Sat Jul 6 2024 A surface front will linger across Georgia through mid-week next week with surface high pressure across the Florida peninsula. Daily sea breezes and an increase in mainly afternoon and evening thunderstorms are expected. Rip Currents: Rip current assessments from near shore buoys continued to indicate a solid Moderate risk for today for NE FL and SE GA beaches with a continued ESE swell down to 0.5-1.5 ft with periods 9-10 seconds. A moderate rip current risk is expected Sunday. && .CLIMATE... Issued at 304 AM EDT Sat Jul 6 2024 Above average temperatures continue today, then high temperatures begin to cool as storminess increases over the area starting Sunday. Today, record high minimum temperatures could be challenged. July 6: KJAX: 79/1902 KGNV: 78/1900 && .PRELIMINARY POINT TEMPS/POPS... AMG 75 93 74 91 / 70 70 50 70 SSI 80 91 79 90 / 10 40 30 60 JAX 76 94 76 92 / 20 60 40 70 SGJ 77 93 77 92 / 10 50 30 70 GNV 75 94 74 93 / 60 60 40 70 OCF 76 95 76 92 / 50 60 30 70 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...Heat Advisory until 7 PM EDT this evening for FLZ021-023-030-031- 035-120-136-220-236-322-422-522. GA...Heat Advisory until 7 PM EDT this evening for GAZ132>136-149-151- 152-162-163-250-264-350-364. AM...None. && $$